Transaldolase is an enzyme involved in pentose phosphate pathways, and plays an important role in biosynthesis and metabolism of aromatic compounds such as aromatic amino acids and aromatic vitamins, nucleic acid-associated substances such as purine-nucleotide and pyrimidine-nucleotide, as well as L-histidine, riboflavin and others [Arch. Microbiol., 164, 324 (1995)]. Accordingly, a transaldolase gene and its gene products are useful as the target in breeding microorganisms for efficient fermentation and production of the metabolites.
As for transaldolase-encoding DNAs, an Escherichia coli-derived gene [Gene Bank Accession Number D13159], a Mycobacterium tuberculosis-derived gene [Nature, 393, 537 (1998)], and Cinecococcus-derived gene [Plant Mol. Biol., 30, 213 (1996)] were isolated; and their nucleotide sequences were determined.
It is reported that the productivity of aromatic compounds in Escherichia coli is increased when its transaldolase activity is increased (WO98/18936).
However, for microorganisms belonging to the genus Corynebacterium that are widely used in amino acid fermentation of industrial importance, there is no report relating to the transaldolase gene and the enzyme encoded by the gene, and the nucleotide sequence of that gene is not known at all.
Regarding saccharide synthesis using transaldolase, an example is reported in which the enzyme is used for producing D-fructose from processed starch [J. Am. Chem. Soc., 114, 6980 (1992)].